This invention relates to microstrip antennas and more particularly to a multi-mode antenna using both microstrip antenna elements and a waveguide cavity.
Compact missile-borne antenna systems require complex antenna beam shapes. At times, these beam shapes are too complex to obtain with a single antenna type such as slots, monopoles, microstrip, etc., and require a more expensive phased array.
Studies indicate that a less expensive approach can be realized in a multi-mode antenna. A multi-mode antenna is a design technique that incorporates two or more antenna types into one single antenna configuration, and uses the unique radiation pattern of each antenna type to provide a combined desired radiation pattern. This requires techniques for exciting two or more antenna modes with one single input feed and also for controlling the excitation of the mode of each antenna type in order to better shape the pattern.